Characterization data of reference materials used for phase II of the priority program DFG SPP 2005 “Opus Fluidum Futurum – Rheology of reactive, multiscale, multiphase construction materials”

A thorough characterization of base materials is the prerequisite for further research. In this paper, the characterization data of the reference materials (CEM I 42.5 R, limestone powder, calcined clay and a mixture of these three components) used in the second funding phase of the priority program 2005 of the German Research Foundation (DFG SPP 2005) are presented under the aspects of chemical and mineralogical composition as well as physical and chemical properties. The data were collected based on tests performed by up to eleven research groups involved in this cooperative program.


Value of the Data
• The aim was to characterize the raw materials as the basis for further research in the DFG SPP 2005 priority program. • The extensive data set illustrates differences in reproducibility depending on the material and the method. • Particularly large variations occurred in the particle size distribution of the limestone powder. • The data can be used as benchmark values for other researchers and may be beneficial for researchers trying to optimize a method used in this study. • The data can be reused by researchers who used the same material or method and need comparative values for their measurements.

Objective
Within the framework of the DFG SPP 2005 priority program a second funding phase containing eleven projects started in spring 2021. Two papers have already been published in Data in Brief for the first funding phase. For the second funding period, the projects have received new materials as a basis for their research. The aim of this dataset is to characterize the raw materials as the basis for further research in the priority program. The data presented will be cited by the imminent research articles by members of DFG SPP 2005. The majority of data are presented as boxplot diagrams. These diagrams include the median line (50th percentile), the range between 25th and 75th percentiles indicated as a box, the range within 1.5 times of the interquartile range (IQR) indicated as whiskers and outliers if present. For a specific explanation, the reader is referred to [2] . Moreover, the mean value is calculated based on the whole dataset (including outliers) and added to the boxplot as a hollow square. Each institute has been assigned a symbol for the entire paper to display the individual measured values. The exact assignment is anonymous. Nevertheless, this representation allows an evaluation of the reliability of the measured values. Based on this representation it can be determined, for example, that outliers always stem from different participants. The symbols of the individual measurements are shown on the right side of the boxplot. The curved line next to the individual measurements represents the measured values as a normal function (Gaussian distribution).
Four different materials were examined. A Portland cement CEM I 42.5 R, a limestone powder, a calcined clay, and a mixture of these three components plus additional anhydrite. The name of the mixture reflects the initial letters of the main components and the ratio of the calcined clay (30 wt.-%) to the rest of the materials (70 wt.%). The properties of this mixture are of interest because it was developed along the lines of the so-called LC 3 cements, developed at the institute EPFL STI IMX LMC [3 , 4] . Compared to pure Portland cement, the mixture is more sustainable due to the replacement of Portland cement with calcined clay and limestone powder.

Characterization Data of Oxide Composition and Phase Contents
Oxide composition, insoluble residue and loss on ignition (LOI) of CEM I 42.5 R, limestone powder, calcined clay and LCC 70:30 were measured according to EN 196-2: 2013 [5] and the results are shown in Fig. 1 . In the sub-images (II) SO 3 * indicates that the value was obtained by X-ray fluorescence analysis (XRF) and SO 3 * * indicates that the value was captured by conventional wet chemistry method. The numbers next to the symbols indicate whether a fused (1) or pressed (2) tablet was measured.   The true densities of CEM I 42.5 R, limestone powder, calcined clay and LCC 70:30 were measured by the Helium pycnometer method according to EN 1097-7: 2008 [7] . Results are shown in Fig. 4 .

Characterization Data of Physical Properties
The specific surface areas of CEM I 42.5 R, limestone powder, calcined clay and LCC 70:30 were measured by the Blaine method according to EN 196-6: 2019 [8] The results are shown in Fig. 5 . The specific surface areas of CEM I 42.5 R, limestone powder, calcined clay and LCC 70:30 were measured by the BET method according to ISO 9277: 2014 [9] . Results are shown in Fig. 6 . The numbers next to the symbols indicate the temperature for sample preparation.
The particle size distributions (PSD) of CEM I 42.5 R, limestone powder, calcined clay and LCC 70:30 were measured by the laser diffraction method according to ISO 13,320: 2020 [10] . The curves were normalized by setting the area below each graph equal to one. The results are presented in Fig. 7 . The shadow areas below and above the average line indicate the scope of the testing results, i.e. highlight potential differences among the participating laboratories. The dashed lines show the individual measurements. Results of CEM I 42.5 R and limestone are based on nine, LCC 70:30 of seven and calcined clay of six measurements. The reproducibility of the PSD measurement of the CEM I 42.5 R is very good. The other materials show much lower reproducibility, particularly the limestone powder. To check whether the large fluctuations were due to different subbatches, a separate round robin test was performed. However, the results also showed large variations as well.

Characterization Data of Further Properties
Some additional properties of the samples CEM I 42.5 R and LCC 70:30 are shown in Figs. 9-12 . The water demand can be seen in Fig. 9 . Fig. 10 shows the initial and final setting times. Both tests were measured according to EN 196-3: 2017 [11] .
The results of isothermal heat flow calorimetry are presented in Fig. 12 . The tests were performed according to the method described in EN 196-11: 2019 [13] with a water to cement ratio of 0.434 at a temperature of 20 °C. The shadow areas below and above each average line indicate the scope of the test results. The dashed lines show the individual measurements.

Experimental Design, Materials and Methods
The material of all groups originates from the same batch and was stored in closed containers. Most of the tests were performed according to the strict procedures described in the following standards. For the characterization of phase contents, powder-XRD combined with quantification of the patterns was used. In different research groups, different XRD instruments with different analysis software were used as shown in Table 2 .

Ethics Statement
This work did not involve human subjects, animal experiments and data collected from social media platforms

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data Availability
Characterization data of reference materials used for phase II of the priority program DFG SPP